1. Field of the Invention
The invention relates to a lens substrate, a lens module, and a fabrication method thereof. More particularly, the invention relates to a wafer level optical lens substrate, a wafer level optical lens module, and a fabrication method thereof.
2. Description of Related Art
With the trend of miniaturizing modules and reducing prices of electronic products, the launch of the wafer level module technology has gained more attention. The wafer level module technology mainly adopts wafer level fabrication technique in electronic products to miniaturize volumes of electronic products and reduce fabrication costs. The wafer level module technology is also applied in the fabrication of wafer level optical lens modules, such that volumes of wafer level optical lens modules can be greatly reduced comparing to that of conventional lens modules. Wafer level optical lens modules are consequently utilized in camera modules of cellular phones, for example.
FIG. 1A is a top view schematically illustrating a portion of a conventional wafer level optical lens module. FIG. 1B is a cross-sectional view illustrating the portion of the wafer level optical lens module depicted in FIG. 1A taken along a sectional line AA′. Referring to FIG. 1A and FIG. 1B simultaneously, a conventional wafer level optical lens module 100 at least includes a lens substrate 110, a first spacer layer 120, a second spacer layer 130, and a pair of substrates 142, 144. The lens substrate 110 has a transparent substrate 112 and at least one lens 114 disposed on both sides of the transparent substrate 112. The lens substrate 110 is located between the pair of substrates 142, 144. The first spacer layer 120 is located between the substrate 142 and the transparent substrate 112 to maintain a first space S1. Moreover, the second spacer layer 130 is located between the substrate 144 and the transparent substrate 112 to maintain a second space S2. The lens 114 is located between the first space S1 and the second space S2, as shown in FIG. 1B.
In the wafer level optical lens module 100, the lens substrate 110 and the spacer layers 120, 130 each adopts an independent substrate. Thus, alignment shift may occur during an adhesion of the lens substrate 110, the substrates 142, 144, and the spacer layers 120, 130 in package alignment, thereby reducing reliability of the fabrication of the wafer level optical lens module 100. In addition, the spacer layers 120, 130 usually adopt transparent materials such as glass or plastics. Therefore, when the wafer level optical lens module 100 performs optical imaging, the stray light passes through the spacer layers easily and cannot be isolated effectively. As a consequence, the noise ratio becomes too high and imaging quality cannot be enhanced effectively.
Furthermore, in the process of fabricating the wafer level optical lens module 100, the lens substrate 110 and the spacer layers 120, 130 each adopts an independent substrate, so that the fabrication costs cannot be reduced easily.